Fire hydrant flow calculation manual

documented procedure for determining the fire flow requirement. Central to provid-ing “enough” water is a determination of how much water should be made available for any given situation. The following definition of required fire flow will be used in this manual: the rate of water flow, at a residual pressure of 20 psi ( kPa) and for. This hydrant is flowing: GPM from the test outlet: Projected available hydrant flow: GPM Note 1: 2nd Static: secondary psi before flowing: 2nd Residual: secondary psi while flowing: The main can be expected to flow about: GPM. Needed Fire Flow Formula To estimate the amount of water required to fight a fire in an individual, non-sprinklered building, ISO uses the formula: NFF i = (C i)(O i)[ + (X + P) i] where NFF i = the needed fire flow in gallons per minute (gpm) C i = a factor related to the type of construction and effective area O.

Gallons per minute is measured by a diffuser with a pitot and a GPM gauge while the hydrant is flowing. NFPA and AWWA predicted flow of any fire hydrant is based on the rated capacity at 20 psi. All hydrants are assumed to provide at least 20 psi. Sample Flow Test Results • Static Pressure (SP) 70 • Residual Pressure (RP) 40 • Gallons Per Minute (GPM) Note - NFPA and AWWA Predicted Flow (PF) is always 20 • Step 1 - (SP - PF) = 50 • Step 2 - (SP-RP) = Needed Fire Flow Formula To estimate the amount of water required to fight a fire in an individual, non-sprinklered building, ISO uses the formula: NFF i = (C i)(O i)[ + (X + P) i] where NFF i = the needed fire flow in gallons per minute (gpm) C i = a factor related to the type of construction and effective area O. Static pressure is taken on a Residual Hydrant with other hydrants closed. Then, an adjacent Flow Hydrant is opened and flow rates are measured at the same time the residual pressure is recorded on the Residual Hydrant. Available GPM at a desired residual pressure (typically 20 PSI) can now be calculated using the Hazen-Williams formula. Fire flow results can then be used to verify a buildings water demand requirements.

The Q formula produces a value in GPM based on the nozzle diameter and pitot pressure (solving for "Q".) Where Q=observed flow, c=coefficient, d=outlet diameter. Next: · Fire Flow Test · Fire Hydraulics: Hydrant Water Available at 20 psi · DIY irrigation part 3 zone planning and gpm bucket tests · Hydrant. 27 thg 7, When requested, the Engineer shall submit the calculations of fire flow requirements and domestic water demands for the project.